By Rachel Webber, College of Agricultural, Human & Natural Resource Sciences
MOUNT VERNON, Wash. – Vegetable and oilseed growers are advised to take extra precautions after an outbreak of three fungal diseases in Pacific Northwest crops, said plant pathologist Lindsey du Toit.
For preventive measures and related information about the outbreaks, view the newly released reports about black leg (http://mtvernon.wsu.edu/path_team/Black%20leg%20in%20Brassiceae%202014%20-%202%20pp%20alert%206-12-14.pdf), light leaf spot (http://mtvernon.wsu.edu/path_team/Light%20leaf%20spot%20OSU%20Disease%20Alert%20in%20crucifers%2017%20June.pdf) and white leaf spot (http://mtvernon.wsu.edu/path_team/White%20leaf%20spot%20OSU%20Disease%20Alert%20in%20Brassiceae.pdf) by plant pathologists Cindy M. Ocamb, Oregon State University, and du Toit, Washington State University.
While only five Washington counties have a quarantine for black leg, the most serious of the three, du Toit said in the coming growing seasons growers across the region should only use certified seed lots that test negative for black leg.
Black leg can be a significant problem in fall- or spring-sown plantings of broccoli, brussels sprouts, cabbage, collard, kale, rutabaga, mustard, canola, rape and other plants in this family. The Pacific Northwest has particularly favorable environmental conditions for the disease, du Toit said.
The most recent outbreaks of all three fungal diseases occurred in Oregon’s Willamette Valley in early spring 2014. In the 1970s, outbreaks of black leg in the eastern and midwestern United States nearly devastated the brassica seed industry as the outbreaks were tied to infected seed lots produced in the Pacific Northwest.
Visit the Pacific Northwest Vegetable Extension Group website, http://mtvernon.wsu.edu/path_team/vegpath_team.htm, for more information about the diseases. See Production of Brassica Seed Crops in Washington State, https://pubs.wsu.edu/ItemDetail.aspx?ProductID=15578&SeriesCode=&CategoryID=&Keyword=062, for more on why black leg and other crucifer diseases have raised concerns about the need for additional quarantines.
Lindsey du Toit, WSU plant pathologist, email@example.com, 360-391-2407